A boat travels against the current from City X to City Y and with the current from City Y to City X ...........

Quantitative Aptitiude (CLAT) Boats and Streams

A boat travels against the current from City X to City Y and with the current from City Y to City X. If the speed of the boat in still water is 40 km/hr and speed of the current is 10 km/hr then find the average speed of the boat for the entire journey.

36.5 Km/hr

34.5 Km/hr

37.5 Km/hr

33.33 Km/hr

Explanation:

When the boat movies in the direction of current then the total speed = Speed of the boat + Speed of the current
= 40 + 10
= 50 Km/hr
When the boat movies in the opposite direction then the total speed = Speed of the boat - Speed of the current
= 40 - 10
= 30 Km/hr
Now to find the average speed of the 2 speeds we can use the formula Average speed = 2ab / (a + b)
Where a and b are the 2 different speeds
Average speed = 2 * 50 * 30 / (50 + 30)
= 1300 / 80 = 37.5 Km/hr